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High-throughput studies of Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 and the effect of carbon coating

High-throughput studies of Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 and the effect of carbon coating
High-throughput studies of Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 and the effect of carbon coating
A two-dimensional sample array synthesis has been used to screen carbon-coated Li(1?x)Mgx/2FePO4 and LiFe(1?y)MgyPO4 powders as potential positive electrode materials in lithium ion batteries with respect to x, y and carbon content. The synthesis route, using sucrose as a carbon source as well as a viscosity-enhancing additive, allowed introduction of the Mg dopant from solution into the sol–gel pyrolysis precursor. High-throughput XRD and cyclic voltammetry confirmed the formation of the olivine phase and percolation of the electronic conduction path at sucrose to phosphate ratios between 0.15 and 0.20. Measurements of the charge passed per discharge cycle showed that the capacity deteriorated on increasing magnesium in Li(1?x)Mgx/2FePO4, but improved with increasing magnesium in LiFe(1?y) MgyPO4, especially at high scan rates. Rietveld-refined XRD results on samples of LiFe(1?y)MgyPO4 prepared by a solid-state route showed a single phase up to y = 0.1 according to progressive increases in unit cell volume with increases in y. Carbon-free samples of the same materials showed conductivity increases from 10?10 to 10?8 S cm?1 and a decrease of activation energy from 0.62 to 0.51 eV. Galvanostatic cycling showed near theoretical capacity for y = 0.1 compared with only 80% capacity for undoped material under the same conditions.
electrodes, rate performance, lifepo4, mg doping, cathode materials, carbon coating, properties, conductivity, phospho-olivines, electrochemical, lithium battery, high-throughput, ion batteries, rechargeable lithium batteries
0378-7753
754-762
Roberts, Matthew R.
773cf85a-e589-406f-8c75-505f6930bd3d
Vitins, Girts
99d664d4-cac7-452a-96e0-768feea6eef2
Owen, John R.
067986ea-f3f3-4a83-bc87-7387cc5ac85d
Roberts, Matthew R.
773cf85a-e589-406f-8c75-505f6930bd3d
Vitins, Girts
99d664d4-cac7-452a-96e0-768feea6eef2
Owen, John R.
067986ea-f3f3-4a83-bc87-7387cc5ac85d

Roberts, Matthew R., Vitins, Girts and Owen, John R. (2008) High-throughput studies of Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 and the effect of carbon coating. Journal of Power Sources, 179 (2), 754-762. (doi:10.1016/j.jpowsour.2008.01.034).

Record type: Article

Abstract

A two-dimensional sample array synthesis has been used to screen carbon-coated Li(1?x)Mgx/2FePO4 and LiFe(1?y)MgyPO4 powders as potential positive electrode materials in lithium ion batteries with respect to x, y and carbon content. The synthesis route, using sucrose as a carbon source as well as a viscosity-enhancing additive, allowed introduction of the Mg dopant from solution into the sol–gel pyrolysis precursor. High-throughput XRD and cyclic voltammetry confirmed the formation of the olivine phase and percolation of the electronic conduction path at sucrose to phosphate ratios between 0.15 and 0.20. Measurements of the charge passed per discharge cycle showed that the capacity deteriorated on increasing magnesium in Li(1?x)Mgx/2FePO4, but improved with increasing magnesium in LiFe(1?y) MgyPO4, especially at high scan rates. Rietveld-refined XRD results on samples of LiFe(1?y)MgyPO4 prepared by a solid-state route showed a single phase up to y = 0.1 according to progressive increases in unit cell volume with increases in y. Carbon-free samples of the same materials showed conductivity increases from 10?10 to 10?8 S cm?1 and a decrease of activation energy from 0.62 to 0.51 eV. Galvanostatic cycling showed near theoretical capacity for y = 0.1 compared with only 80% capacity for undoped material under the same conditions.

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e-pub ahead of print date: 30 January 2008
Published date: 2008
Keywords: electrodes, rate performance, lifepo4, mg doping, cathode materials, carbon coating, properties, conductivity, phospho-olivines, electrochemical, lithium battery, high-throughput, ion batteries, rechargeable lithium batteries
Organisations: Chemistry

Identifiers

Local EPrints ID: 150639
URI: http://eprints.soton.ac.uk/id/eprint/150639
ISSN: 0378-7753
PURE UUID: effea497-c399-4ada-bc5e-05d17d0bebf0
ORCID for John R. Owen: ORCID iD orcid.org/0000-0002-4938-3693

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Date deposited: 06 May 2010 14:20
Last modified: 03 Dec 2019 02:03

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